1. Field of the Invention
The present invention relates to an optical encoder designed to detect the relative displacement between an encoder scale and an encoder head.
2. Description of the Related Art
In recent years, to miniaturize optical encoders and lower their manufacturing cost, with regard to encoder head shape, can-package light sources and light-receiving elements have been replaced by bare-chip or surface mounting types or have been encapsulated in clear mold resin.
Further, the light-receiving element is covered with or encapsulated in a light transmission member such as clear mold resin. Moreover, both the light-emitting element and the light-receiving element are encapsulated together.
For example, in the optical encoder of FIG. 10, which is disclosed in Jpn. Pat. Appln. KOKAI Publication No. 6-221874, the light-emitting element 8 and the light-detecting element 12 are sealed in a transparent capsule 2 made of epoxy resin or the like. The transparent capsule 2 has two lenses 40 and 41 on the surface. The light emitted from the light-emitting element 8 directly impinges on a code wheel 34 that has a reflecting region 30 and a non-reflecting region 32. The light reflected from the code wheel 34 is detected by the light-detecting element 12.